The classic slide guitar technique originated in the deep South long ago, evolving through a number of musical genres from Gospel to Rock & Roll. It has always been primarily a staple of blues, folk, country and rock guitarists and was usually called "bottleneck" guitar playing, because the players generally used the neck of a glass bottle to fret the notes on an acoustic guitar. The "bottleneck" sound is one-of-a-kind.
However, when a glass slide is used on a metal string the glass will wear down. This impedes movement of the slide across the strings and affects the quality of the resulting sound. Glass also breaks when dropped and is dangerous when broken.
Many variations of the bottleneck have been developed in an attempt to produce its unmistakable sound. Over the years, the variations have achieved varying degrees of success, but no product has been able to capture that elusive tonality of glass on metal strings, combined with the ease of playing comfort sought by acoustic and electric musicians alike.
The most common slide currently in use is a chrome-plated tube that slips over the musician's finger. However, the chrome plating on the tube will frequently begin to wear after about one year. Once the chrome plating is removed or worn the tube will begin to corrode. Any wear or corrosion on the surface of the slide will effect the quality of the sound achieved and the ease of movement of the slide across the strings. Additionally, although chrome plating is visually a smooth surface, the surface is substantially more porous than glass and therefore effects the sound and ease of sliding across the strings.
It is believed prior metallic guitar slides did not have a surface finish of better than twenty to thirty-two microinches.
A need therefore exists for a guitar slide which is resistant to wear caused by the guitar strings, is non-corrosive and which has a smoothness comparable to glass.